Tesla is an HTTP client that leverages middleware to streamline HTTP requests and responses over a common interface for various adapters.
It simplifies HTTP communication by providing a flexible and composable middleware stack. Developers can easily build custom API clients by stacking middleware components that handle tasks like authentication, logging, and retries. Tesla supports multiple HTTP adapters such as Mint, Finch, Hackney, etc.
Tesla is ideal for developers who need a flexible and efficient HTTP client. Its ability to swap out HTTP adapters and create custom middleware pipelines empowers you to make different architectural decisions and build tools tailored to your application’s needs with minimal effort.
I would appreciate any feedback about it. I need a different perspective to make sure the documentation covers most personas. The In-Module documentation is still WIP; I focused on guides and the getting started experience.
Req is excellent for getting something working very fast. At the same time, I use Tesla for predictable SDKs since Tesla barely includes anything by default, and Tesla has been around and used in production quite a bit.
You can check the built-in steps/middleware and the defaults you like; to me, they are the same, just different starting points.
For me Tesla.Middlewear.Logger is great for debugging as you can log the whole request/response. I believe the architecture of Req makes this difficult as there is no way to hook into the entire communication cycle.
I also find that the Tesla Middlewear model is simpler than Req’s, which requires more boilerplate and is a bit harder to get your head around, at least that was my impression from writing equivalent middlewear for both clients:
Tesla:
def call(%Tesla.Env{method: :get, url: url} = env, next, options) do
timeout = Keyword.get(options || [], :debounce_timeout)
case Boing.debounce(url, timeout) do
:ok -> Tesla.run(env, next)
{:error, debounced: ^url} -> {:error, debounced: url}
end
end
Req:
defmodule DebouncedException do
defexception [:url]
@impl Exception
def message(%__MODULE__{url: url}), do: "Debounced: #{url}"
end
def attach(%Req.Request{} = request, options \\ []) do
request
|> Req.Request.register_options([:debounce_timeout])
|> Req.Request.merge_options(options)
|> Req.Request.append_request_steps(debounce: &debounce_step/1)
end
defp debounce_step(%Req.Request{method: :get, url: url} = request) do
timeout = request.options[:debounce_timeout]
case Boing.debounce(URI.to_string(url), timeout) do
:ok -> request
{:error, debounced: url} -> {request, DebouncedException.exception(url: url)}
end
end
